Ahhh--Problem solved. Adding a REL sub-bass unit...


I'm wondering how many audiophiles have given up on loudspeakers preamturely, or have gone down the rabbit hole of cable swapping to "fix" an issue with their speakers.  

I grew up hating subwoofers and home theatre.  I still haven't come around fully to home theatre.  I've warmed up though.  I've had my own issues with otherwise great loudspeakers, including a pair of Klipsch Forte IIIs.  I was very frustrated as I'm feeding them from a respected tube integrated, I've tried them with a 300B amp, and I've toiled over positioning.  

The issue that I was having was the mids and highs were dominating in my room--despite the size of the woofer and passive radiator. Some recordings were just too bright.  Sometimes I felt the speaker, however "alive" and dynamic was not imaging well, needed soundstage help, and so on.  

I hate to say the REL T9i I threw in the mix today is a panacea because there's always stuff to tweak.  Yet I have experienced this before with a Sumiko subwoofer.  Adding one to the mix and dialing it in so that it's barely audible has brought everything into focus.  Everything is more relaxed and energetic at the same time.  

I'd say that the REL is a room tuning device above all.  I have a larger room (I think it's 15 wide, 24 long and 10 high--in feet).   I'm not sure how much I'd have to spend or what different choices would solve this otherwise.  From a guy that used to reject subwoofers out of hand (my bias came from the 90s home theatre craze) I think that they might be necessary in the lion's share of systems with the lion's share of speakers.  To say, "you don't need a sub" with speakers might be true depending on your room, but I also think in most situations you are missing out on what they can do for so many criteria that are not necessarily in keeping with adding bass--e.g. soundstage, focus, imagine, fullness, taming treble, etc.). 

Finally, I really wish that I could try some other brands as many audiogon members recommended so many respectable names.  I ultimately went with REL because of its philosophy, my similar experience with a Sumiko sub (within the family of REL or somehow related), and the high frequency input connections. 
128x128jbhiller
If you do this with the REL you are not using the high level speakon connectors, no?
RELs are specifically designed to have the mains run through their entire frequency range. REL's manual highly advises to only use the high level speakon connector because it performs the best in that way. (I have tried REL subs using the high level connector and not using the high level connector.) This does not mean the REL doesn't provide flexibility. But it does mean it is designed to fully integrate with the mains by taking its timing cue/signal from the same amplifier was the mains, without deriving its power from the mains' amplifier--the concept being that the mains amplifier allows the REL subs and the subs to be "colored" with the same signal. The RELs allow the user to crossover from 30Hz to 120Hz, to select "0" or "180" phase and to control volume/gain. REL recommends running their subs at the lower end of the crossover range and at a  relatively low volume. I'm currently running a three REL "swarm"--it works really well.    
2 things I am thinking about with REL:

1.)Will it go low enough for my liking? (I don't get the warm and fuzzies from only going to 28Hz on the T/9i
2.)Would I be better off, as in, better integration integration with my mains if I went the Vandersteen approach and used the low slope high-pass filters combined with the high-level speaker connection with a 2wq. Not only that, but the 2wq hits to 20Hz and is considerably heavier and is also known for being an extremely musical sub.
It seems like I might be better off with the Vandy, but I get the feeling I shouldn't discount the RELs (They are somehow calling my name, LOL)
@bstatmeister I received my second sub yesterday and WOW!I'm more impressed than I was expecting.The soundstage widened and feels more enveloping somehow.The performers seem more anchored in place,if that makes sense.Instead of the sax player being off to the left he is standing exactly two feet from center and five  feet back(one example).I'm hearing the effects of the beginning of cancellation of reflections and room modes.I'm lovin it!The bass is a little more articulate,I was happy with it before but the room seems more evenly pressurized now.
Right now the sub's are positioned behind and slightly to the inside,firing diagonally towards the opposite corners hooked up with their line level inputs.It sounds better in my room rather than running them at speaker level.I'll get some cheap longer cables and fool around with different placement but it really sounds good as is.I'm definitely going to add two more in the future.

Best of luck to you as you research and looking forward to your decision and results:)
@ieales What do you recommend for a single capacitor that is "plug N' Play"?
(that is minimal DIY)
Keep in mind
Isn't the reason you are thinking of doing this is to improve the whole system?

 If that's not what your after please don't let me keep you from having fun wondering about it.

If you agree that introducing a sub and or subs your goal is to do no harm,

Harm is for example overloading the room at room resonance blinding you to all the musics clarity you used to have.

 Harm is adjusting the sub down at the room resonance but failing to achieve a smooth overall in room response at the listening chair.

 Harm is slowing up the musics cadence pace and transient snap across the board and ending up with a lot of 90 hz or whatever frequency smearing the quality in your music.

Vandersteen Sub 3s and High Pass together with room compensation address a total solution with whole system improvement

The High pass simply connects to your main amp, unloading the main amp of its heavy lifting, but most importantly dramatically lowers the inter modulation distortion within your main speakers cabinet allowing them a new level of performance, next the11 bands per sub analog adjustments built into Sub Three amps are adjusted to fix (y o u r particular R o o ms) anomalies achieving a smoother in room bass response, improving your musics pace,transient snap, dynamics, clarity and transparency while maintaining all that's good with what you have.

 Best JohnnyR
 Audio Connection
 Vandersteen dealer 29 Years
 

What do you recommend for a single capacitor that is "plug N’ Play"?

This image shows the circuit topology of hi pass

f = 1 / (2πRC)

f in Hz
R in Ohms of amplifier input
C in Farads of series cap

C = 1 / (2πfR)

This calculator will do the math. Scroll down to the calculator. Select Calculate Capacitance, enter amp input R & corner frequency. Calculation is pF. Best dielectrics are Teflon, polystyrene, polypropylene in that order and descending cost.

Parallel if you want to exact frequency, but ±1nF is close enough for most amps except those with very high input impedance. If you want to go nuts get an LCR meter and match as tight as you like, but realize the speakers are not that close, especially at the bottom!

This image from http://www.ielogical.com/Audio/#SmallestThings shows how to assemble.

You feed the full range to the sub, using its controls to roll out the highs and feed the filtered side to the mains.

When connecting for first time, disconnect mains from amplifier and turn subs all the way down. Slowly bring up subs with program playing. Should be just low end. Turn off program. Measure amp Output voltage. It should be nearly 0mV.

PM any questions.
Rolling the bass out of the mains is unnecessary as the mains were likely designed to run full range, and in my experience with a few differing speakers used with my 2 RELs, that's simply a better sounding way to go. My 8" and 10" RELs match extremely well with the 12" bass speaker in my Heresy IIIs, with no phase issues (why would there when the phase is adjustable and the subs are barely in the same frequency range as the main speakers?). I don't think the avalanche of technical worries heaped on those deciding to use a sub or two is helpful really. I test my mains with a testing CD to decide where the bass becomes reticent, move the subs around until things sound great in my listening spot, and only change the sub levels from time to time to suit my mood or deal with too much or too little bass in a recording. Easy.
Ouch! on so many levels.

Low end is always the poor stepchild as it conflicts with parameters necessary for higher range of driver.

Phase controls adjust at single frequency. See http://ielogical.com/assets/SubTerrBlues/PhaseControl.png at http://ielogical.com/Audio/SubTerrBlues.php/

Smaller sub than main driver? Really!
Different sub models? Really!

Testing CD and no instrumentation? REALLY!

Easy == compromised.

I'd have to hear it to be convinced.